BR112016008673B1 - METHOD TO ACHIEVE A FAST RESPONSE TIME OF A POLYCARBOXYLATE ETHER POLYMER IN A CONCRETE MIXTURE - Google Patents

Abstract

fast response time in slump monitoring systems. The present invention provides a rapid response method and system in which one or more honeycomb-type polycarboxylate ether (pce) polymers, which have a cumulative adsorbity coefficient in the range of 40% to 75%, are employed as addition mixtures. fluidizers dosed into the concrete through, and in automated slump monitoring and control systems that iteratively monitor and adjust the slump of the concrete mix.

Description

FIELD OF THE INVENTION

[001] The present invention relates to the manufacture and processing of hydratable cementitious compositions, such as concrete, and more particularly, to a method and system for achieving rapid response time with the use of polymer cement dispersants. polycarboxylate ether base that have a cumulative adsorbity coefficient of 40% to 75% and enable slump monitoring systems to operate faster and more effectively, specifically when operating in iterative modes that may otherwise degrade concrete delivered.

Background of the Invention

[002] The term "response time", as used herein, refers to the mixing time or mixing energy required to achieve a "target" slump (desired level or fluidity state) of wet concrete in a drum of rotary mixing. Response time is often described in terms of the number of mixing drum revolutions required for the wet concrete to achieve a target slump after a fluidizing addition mix is dispensed into the mixing drum.

[003] A ready mix concrete delivery truck may need to rotate the mixing drum for 15 to 20 revolutions or more in order to mix naphthalene sulfonate or water type dispersants evenly throughout a load of concrete before the target drawdown is achieved. Polycarboxylate type superplasticizers may require 50 to 70 or more revolutions of the concrete mixing drum before achieving complete and uniform dispersion in the concrete mixing charge. This behavior requires considerable planning and perspective in delivering concrete that has a desired slump at the time of pouring.

[004] Although the concrete delivery truck travels on the road to the dump site, the maximum revolutions per minute (rpm) of the mixing drum is around 4 to 5 rpm. When the truck is stationary (parked), the loaded concrete mixing drum can rotate at a maximum rate of approximately 20 to 40 rpm. If a target slump (a specified slump level) is to be achieved during travel and before the mix load reaches the dump site, it may be necessary to introduce a polycarboxylate superplasticizer into the concrete mixing drum for approximately 20 minutes. or more before reaching the dump/build site so that there is sufficient processing time to reach the target drawdown. Alternatively, when the mixing truck arrives at the dump/construction site, the add-on mix can be introduced into the concrete and the mixing drum rate can be increased up to 20 to 40 rpm while the truck is parked so that the mix by fluidizing addition can be dispersed uniformly throughout the batch, theoretically, in minutes.

[005] However, concrete delivery trucks typically require 50 to 70 rotations of the mixing drum, or more, before an accurate slump measurement is obtained, according to current practice. Before onboard slump monitoring systems were available, concrete slump was measured using the standard slump cone procedure on a sample of mix taken from the mixer. The use of slump cone measurement in the workplace is still common practice as the industry deals with a number of variables - temperature, hydration and humidity, environment, day quality for day materials - that can impair chemical monitoring and dosing. accurate, even when automated sag monitoring systems are used.

[006] In the U.S. Patent 8,058,377 B1 issued on November 14, 2011 and jointly owned by the present assignee, Goc-Maciewjeska et al. Disclosed are phosphate-containing polycarboxylate polymer dispersants that contain monoester, diester, and triester groups in specific molar ratios to achieve "rapid internal mix dispersibility" compared to polycarboxylate polymer dispersants that do not contain phosphate groups. Such phosphate-containing polymers impart improved “initial” slump as well as slump “hold” to the concrete mix. Goc-Maciewjeska et al. believed that the blend dispersibility of such polymers would be "particularly useful in ready-mix delivery trucks or in plant batch operations, whereby "time can be saved through the ability of the polymer dispersant to become uniformly distributed throughout a concrete mix in less time compared to polycarboxylate polymers that do not contain phosphate groups" (See document in U.S. 8,058,377 column 2, II. 23 to 29).

[007] Goc-Maciewjeska et al. explained that this "relatively faster mix dispersibility will be highly useful in automated mixer systems where concrete slump is monitored within a rotating drum mixer and adjusted through the dosage of a rheology modifying agent (e.g. , mixing by chemical addition, such as a superplasticizer or water reducer) into the mixture." (See U.S. document 8,058,377 in column 2, lines 30 to 35). It is further explained that after dosing the admixture mix and mixing the concrete, the energy required to turn the mixer is monitored until the energy curve flattens out over time, thus indicating that the dose has been dispersed evenly. inside the mix. Certain phosphate-containing polymers have been found to disperse more quickly in the concrete mix compared to polycarboxylate polymers that do not contain such phosphate groups, thus shortening the time required in automated slump monitoring operations. (See U.S. document 8,058,377 in column 2, lines 35 to 42).

[008] There is a need for fast response time ("internal mixing" dispersibility) for polycarboxylate fluidizing polymers used in automated systems that measure the energy required to turn the rotating mixing drum until the energy curve becomes flat. over time (thus indicating that the blend dose by addition is evenly dispersed in the mixture), as the metering and monitoring is performed iteratively, which extends the theoretical internal mixing time to the blend metering by fluidizing addition to concrete. A first batch of admixture mix is dispensed into the concrete and the slump is monitored via the automated system over time (i.e. over several mixing drum revolutions) and then the slump data readings are compared. with pre-registered data stored in processor-accessible memory; and then one or more subsequent doses of the fluidizing addition mix are dispensed into the concrete where a discrepancy is detected through the system between the actual and target slump levels; and then the concrete load is again monitored over additional drum revolutions until the target slump is achieved. If a sufficient discrepancy still exists, the process can be repeated one or more times. Such automated slump monitoring systems are disclosed, for example, in U.S. Patents. 8,311,678 and in the U.S. 8,491,717 (Verifi, LLC), incorporated herein by reference.

[009] "Response time" has not been given serious consideration as a primary or even desirable attribute of honeycomb-shaped polycarboxylate ether ("PCE") cement dispersants until the present invention.

[010] Therefore, it is an object of the present invention to provide a method and system for achieving a fast turnaround time with the use of one or more polycarboxylate ether-based polymer cement dispersants that have a cumulative adsorbity coefficient of 40% to 75%, thus enabling lowering monitoring systems to operate faster and more effectively. Due to the fact that automated slump monitoring systems must sample the concrete by rotating the drum several times to sample the energy required to rotate the drum and translate it into a slump reading and then rotate the drum several times to internally mix a mix by fluidizing addition, the numerous drum revolutions can draw too much air into the concrete mix and can also overheat the cement due to the crushing action of the aggregates. Thus, for the present inventors, achieving a fast response time is particularly desirable when the slump monitoring system needs to operate iteratively (monitor, adjust sag, monitor, adjust sag, etc.), which might otherwise , tend to degrade the delivered concrete.

SUMMARY OF THE INVENTION

[011] The present invention provides a method and system for achieving rapid response with the use of a chemical fluidizing addition mixture comprising at least one and possibly two or more honeycomb-type polycarboxylate ether polymer or polymers (hereinafter "PCE ") as the main cement dispersing components, dosed into the concrete using an automated slump monitoring system.

[012] The present inventors have surprisingly found that fast-response internal mix dispersibility can be achieved using PCE(s) that have a cumulative adsorbance ("Ac") coefficient of 40% to 75% (as measured at 25 degrees Celsius) when mixed in a sample of cement mortar within 120 seconds after mixing to obtain an aqueous cementitious slurry, wherein the water to cement ratio is 0.4 and the total amount of PCE (s) dosed into the cement is 0.03% to 0.5% by dry weight based on the weight of the cement, wherein the dosage of PCE(s) is determined through a mortar test whereby the dosage of PCE(s) is of PCE administered is equivalent to that which achieves a 14% reduction of water in the cementitious mixture. In other words, the amount of PCE polymer(s) used is that which would achieve fluidity improvement equivalent to adding 14% additional water to the cementitious mix.

[013] The use of substantially less than optimal PCE adsorbability is surprising and counterintuitive, as conventional thinking is that PCEs that have the fastest response time would be the polymers that attach to cement particles most aggressively. It was previously thought that honeycomb-type PCEs, especially with their adsorption backbone units and hydrophilic polyoxyethylene side chains (or "teeth"), should work to disperse particles more effectively if they Aggressively adhere to the solid-liquid interface of the cement to alter the initial slump through the use of hydrophilic groups to create a repulsion within the particle-water mixture, thus achieving a fluidity within the concrete while at the same time reducing the ratio of water to cement.

[014] Unexpectedly, the present inventors have found that the quick response, in terms of fast internal mixing of the PCEs into the concrete, is most ideally achieved, not through the use of PCEs that have the fastest impact on initial slump, but through the use of PCEs that, to date, can be considered to confer a “long-term” drawdown enhancing effect. In other words, the polymers that worked best to achieve the fast response are those that tend to enhance or retain sag, rather than those that affect initial sag behavior.

[015] The present inventors believe that for rapid response using automated slump monitoring systems, PCEs must have less than 75 percent of the cumulative adsorbance ("Ac") coefficient with respect to cement particles in the concrete (when quantified using analytical adsorption methodologies that are known and described in detail hereafter).

[016] Thus, an exemplary system of the present invention for achieving fast mixing response time by chemical fluidizing addition in a hydratable cementitious mix comprises: a rotating mixing drum for containing a hydratable concrete mix; a system for continuously monitoring the slump of the hydratable concrete mix contained in the rotating mixing drum and for dispensing controlled amounts of fluidizing chemical addition mix into the concrete mix within the drum based on continuous monitoring; and a fluidizing chemical addition mix to be dispensed through the system into the hydratable concrete mix contained in the rotating mixing drum, wherein the addition mix comprises at least one honeycomb-type polycarboxylate ether polymer to modify the lowering of the concrete mixture (wherein the one or more honeycomb-type polycarboxylate ether polymer or polymers are hereinafter referred to as "PCE"), wherein the PCE has a cumulative adsorbity coefficient (Ac) of 40% to 75% , as determined through a depletion method whereby a sample of the PCE was obtained in an aqueous cement slurry containing the cement used to produce the slurry of hydratable concrete, wherein the aqueous cement slurry is separated after 120 seconds mixing of the aqueous cement slurry containing PCE to obtain supernatant capillary water, according to the formula Ac= [(A - B)/A] x 100, where "A" represents the amount total of P EC added to the aqueous cement slurry prior to separation to obtain the supernatant capillary water, "B" represents the amount of PCE remaining in the supernatant capillary water obtained by separating the aqueous cement slurry after mixing for 120 seconds , and wherein the adsorbity is measured at 25° Celsius in the capillary water of supernatant separated from the aqueous cement slurry after a 120 second mixing of the aqueous cementitious slurry containing the cement, water and PCE, wherein the water ratio for cement from the slurry is 0.4 and the amount of PCE dosed into the aqueous cementitious slurry is between 0.03% to 0.5% by dry weight, based on the cement and is calculated by mortar testing , whereby the dosage for the PCE is one that would provide the same flowability as adding 14% additional water to the aqueous cementitious slurry.

[017] Accordingly, an exemplary method of the present invention that achieves rapid response time of a polycarboxylate ether polymer in a concrete mix comprises: providing a rotating mixing drum to contain a hydratable concrete mix; provide a system for continuously monitoring the slump of the hydratable concrete mix contained in the rotating mixing drum and for dispensing controlled amounts of fluidizing chemical addition mix into the concrete mix within the drum on the basis of continuous monitoring; and providing a fluidizing chemical addition mix to be dispensed through the system, wherein the addition mix comprises at least one honeycomb-type polycarboxylate ether polymer to modify the slump of the concrete mix (wherein the one or more polymer or honeycomb-type polycarboxylate ether polymers are hereinafter referred to as "PCE"), wherein the PCE has a cumulative adsorbity coefficient (Ac) of 40% to 75%, as determined by a depletion method, by means of of which a sample of the PCE is loaded into an aqueous cement slurry that contains the cement used to produce the hydratable concrete mix and mixed together, and separated after a continuous 120 second mixing of the aqueous cement slurry to obtain supernatant capillary water, according to the formula Ac= [(A - B)/A] x 100, where "A" represents the total amount of PCE added to the aqueous cement slurry which was then separated to get capil water supernatant air, "B" represents the amount of PCE remaining in the supernatant capillary water obtained by separating the aqueous cement slurry, and where the adsorbity is measured at 25° Celsius in the supernatant capillary water separated from the slurry of aqueous cement after 120 seconds continuous mixing of the aqueous cementitious slurry containing the cement, water and PCE, wherein the water to cement ratio of the slurry is 0.4 and the amount of the PCE dosed into the cementitious slurry water is between 0.03% to 0.5% dry weight based on cement and the dosage of PCE used is calculated through the mortar test, whereby the dosage for PCE is that which would provide the same fluidity than adding 14% additional water to the aqueous cementitious slurry.

[018] The laboratory equipment needed to mix the PCE sample into the cementitious slurry, to separate capillary water from the supernatant (e.g., filter), and to determine the amount of PCE in the supernatant is readily available and straightforward in terms of deployment. Automated slump monitoring systems contemplated for use in exemplary systems and methods of the invention are commercially available and are also relatively straightforward in terms of use. Preferably, the systems are installed on concrete delivery trucks and have at least one sensor to measure the energy required to rotate the concrete mixing drum and at least one sensor to measure the rotational mixing speed of the mixing drum and, Preferably, the slump monitoring system is programmed to relatively continuously monitor and adjust the slump by introducing fluidizing chemical addition mix into the concrete load and, if necessary, repeat the monitoring and adjustment steps accordingly. iterative during transit and/or upon arrival at the dump/delivery location.

[019] In additionally exemplary modalities, automated slump monitoring systems can employ sensors that are rheological probe units immersed in the concrete or mortar contained in the mixing drum and that measure at least a value indicative of a rheological property of the concrete. or mortar (eg slump, slump flow, elastic tension, viscosity, etc.). Preferably, such probe units are mounted to an inner wall and/or mixing blade within the mixing drum.

[020] The advantages and additional features of the present invention can be described in greater detail hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[021] An observation of the benefits and features of the present invention can be more readily understood by considering the following written description of preferred embodiments in conjunction with the drawings, wherein

[022] Figure 1 is a schematic diagram of an exemplary system and method of the invention for achieving rapid response using one or more honeycomb-type polycarboxylate ether ("PCE") polymers that have a cumulative adsorbity coefficient (Ac) of 40% to 75% within a wet concrete mix load monitored through an automated slump monitoring and control system;

[023] Figure 2 is a plan view taken along a rotational geometric axis of the exemplary rotating mixing drum of Figure 1 which contains a concrete mixture containing PCE cement dispersant;

[024] Figure 3 is a graph illustrating the present invention, whereby a laboratory sample of fluidizing PCE cement dispersant at 120 seconds after mixing (a horizontal axis shows mixing time), as designated by the double arrow in "(a)," has a cumulative adsorption coefficient of 40% to 75% (a vertical axis shows an adsorption coefficient or percentage in cement in a mortar sample mixture) and behavior along the time of such PCE is plotted using solid lines (which define the designated area "2"); and this is compared to the polymer behavior (indicated using dotted or dashed lines) of polymers that have an adsorbance behavior that is either very slow ("3") or very fast ("1");

[025] Figure 4 is a graph illustrating the concept of "response time" through the use of test data of equivalent cement mortar with a mortar mixer, whereby mixing effects by adding fluidizing PCE introduced into the concrete contained in a rotating concrete mixing drum are illustrated in terms of the mixer power required to rotate the drum over time (seconds of mixing time starting with the addition of PCE polymer mix);

[026] Figure 5 is a graph illustrating the change in engine power through PCE polymer cement dispersant additions;

[027] Figure 6 is a graph that illustrates the relationship between the response time and the percentage of PCE adsorbed at the required dosage (equivalent amount of PCE needed to achieve 14% water cut in the concrete mixture) of polymers synthesized in laboratory;

[028] Figure 7 is a graph illustrating the relationship between response time and percentage of various commercial PCE polymer cement dispersants (equivalent dosage to achieve 14% water cut-off in the concrete mix); and

[029] Figure 8 is a graph illustrating the relationship between PCE polymer adsorption after a two-minute mixing of laboratory sample into cement mixture (vertical geometric axis) as a function of PCE polymer dosage percentage by weight based on the weight of cement.

DETAILED DESCRIPTION OF PREFERRED MODALITIES

[030] Automated monitoring systems to monitor and adjust one or more concrete properties, such as slump, are contemplated for use in the present invention. These include the type of monitoring systems that measure the energy or hydraulic pressure required to turn the mixing drum containing the concrete and correlate this to the rheological property (eg slump) that is monitored. These also include the type of monitoring systems that employ load cell sensors or probes that are attached to the inner wall of the concrete mixing drum and/or to mixer blades mounted on the inner wall of the concrete mixing drum. concrete. Exemplary monitoring systems for measuring the hydraulic pressure required to rotate the concrete lowering mixing drum are commercially available from Verifi LLC, 9466 Meridian Way, West Chester, Ohio, USA and also 62 Whittemore Avenue, Cambridge, Massachusetts , USA. VERIFI® type slump monitoring systems are variously disclosed in the patent literatures authored by Verifi LLC. They include the U.S. Patent. 8,118,473 to Compton et al.; the document in the U.S. 8,020,431 to Cooley et al.; the U.S. Patent 8,491,717 to Koehler et al.; the U.S. serial number document. 10/599,130 to Cooley et al. (U.S. Publication 2007/70185636 A1); the U.S. serial number document. 11/834,002 to Sostaric et al. (U.S. Publication 2009/0037026 Al); and the U.S. serial number document. 258,103 to Koehler et al. (Publication No. 2012/0016523 Al), all of which are incorporated by reference herein. In the document in the U.S. 8,491,717, Koehler et al. believed that the slump monitoring system could track the dosage of both PCE cement dispersants and air control agents (air capture and/or evacuation agents) based on nominal dosage profiles that were stored in the slump. memory.

[031] It is further believed that exemplary monitoring systems that employ a probe or other electromechanical sensor to detect the force applied through the concrete on the probe or sensor are suitable for use in the present invention. For example, the Publication of in the U.S. 2012/0204625 Al (Order Serial Number 13/500,643), de Beaupre et al. (attributed to I.B.B. Rheologie Inc.) revealed a probe, installed on the drum lid of the ready-mix truck, which comes into contact with the concrete and measures the resistance pressure imparted by the concrete. Values or derived values obtained from sensor readings can be used to calculate at least one rheological property of concrete contained and rotated within a mixing drum. For this reason, the present inventors believe that electromechanical sensors or probes can also be employed within automated monitoring systems suitable for use in the present invention.

[032] Another concrete slump measurement and control system is disclosed in the Publication of in the U.S. 2011/0077778 Al de Bertold Berman (attributed to Dully Datzeff-Berman). See also WO 2009/144523. Berman discloses an apparatus and method for measuring and controlling the slump of concrete through the use of a monitoring sensor within the interior surface of the concrete mixer. Berman's apparatus and method involve controlling mixing and slumping through the use of sensors that measure the force applied by the concrete, both as pressure and as stress on the inner surface of the mixer. Berman claims that the pressure or stress on the sensors is directly related to the sag value. In this way, by monitoring the forces on the sensors, the desired concrete mix slump can be obtained. Consequently, Berman teaches that the required additional liquid or solids can be added in a way that matches the forces on the sensor and therefore the desired sag. The Berman apparatus is believed to be commercially available from Sensocrete of Saint Lazare, Quebec, Canada under the tradename Concrete Optimizer™.

[033] Another exemplary electromechanical device for monitoring concrete mixing which the present inventors believe is suitable for use in the present invention is disclosed in European Patent Application No EP 1 961 538 A2 by Eugenio Bonilla Benegas (Application No 06847054.1) . Similar to the Sensocrete system, the Benegas automatic monitoring system employs a sensor that rotates integrally with the concrete mixing drum, however, the Benegas sensor is fixed or connected to the mixing blade and is sensitive to the stresses exerted by the concrete. or mortar on the blade and the values detected through the sensor can be communicated via radio communication or other similar wireless means of communication to another location separate from the sensor. For that reason, the automated monitoring systems exemplary of the systems and methods of the present invention are selected from the group consisting of power sensors (e.g., hydraulic pressure sensor to detect the hydraulic pressure required to rotate the drum of mixing), as well as sensors or electromechanical probes that detect pressure or stress exerted by moving concrete that is rotated inside the mixing drum. In any case, the signal values emitted by such various types of sensors can be fed to a processor unit to provide an indication of or a signal correlated to a rheological property of the mixture contained in the mixing drum.

[034] The aforementioned automated monitoring systems can incorporate or be employed in combination with other sensors, such as temperature sensors, to provide various additional values that can be taken into account while monitoring and adjusting concrete during transit.

[035] Accordingly, the present inventors believe that a variety of automated monitoring systems and devices are suitable for use in the present invention, and the teachings of the various publications mentioned above are incorporated herein by reference as if they were fully established. in this document. Thus, while specific reference may be made to the use of hydraulic pressure sensors in the present document as a currently preferred way to correlate detected values to one or more properties of concrete or mortar contained in the concrete mixing drum, it will be understood that the sensors Electromechanical data can be replaced by hydraulic pressure value readings that can be correlated to one or more concrete or mortar properties, such as slump, slump flow, tensile stress, viscosity and/or other properties of the mixture.

[036] As illustrated in Figure 1, an exemplary system 10 and method of the present invention for achieving fast response time comprises a rotating concrete mixing drum 12 that has at least one, and more preferably at least two, mixer blades (13A and 13B) mounted on the inner wall of mixing drum 12 and arranged generally spirally or helically around the rotational geometric axis of mixing drum 12 which is designated by the dotted line (as at 30). Mixing drum 12 is rotatably mounted on a concrete delivery vehicle (not shown). Mixing drum 12 shall have a capacity to hold up to 10 cubic yards (7.65 m3) or more of fresh concrete 15. System 10 further comprises a motor drive assembly (such as a motor drive assembly driven by hydraulic pressure pump which is designated in 16) or other type of motor mechanism or pump assembly for rotating the mixing drum 12 which contains the concrete and further comprises a sensor, such as a hydraulic sensor 17, coupled to the motor or pump mechanism 16 to monitor the energy required to rotate the mixing drum 12. A computer processor unit 20 may be coupled or wirelessly connected to the hydraulic sensor 17, as well as a second sensor 22 to detect the rotational speed of the mixing drum 12 and to a device, such as a pump, valve, or other dispensing device for dispensing chemical addition mixture (designated as at 25) into the concrete mixture 15 contained in the drum mixer 12 via the signal or other instruction of the processor unit 20.

[037] Although mixing drum 12, hydraulic motor assembly 16 and hydraulic sensor 17 and chemical addition mixing and pump device (generally designated at 25) are understood to be located on a concrete delivery truck (not shown), it is understood that the computer processor 20 may be located on the truck or at another location, such as a remote location, and that, instead of wires, it is possible that transmitters and receivers may be used to connect, wirelessly, various system components 10 such as speed sensor 22, accelerometer 24 or other sensors to the processor units. Thus, in an alternative exemplary embodiment, an accelerometer sensor 24 mounted on the outer surface of mixing drum 12 may be coupled to a wireless transmitter (not shown) to transmit signals from the accelerometer sensor 24 to the processor unit 20 to provide signals that can be converted by processor unit 20 to obtain the rotational speed of mixing drum 12. In an additional embodiment, accelerometer sensor 24 may be coupled or integrated with a separate wireless processor and transmitter unit (not shown). to calculate and to transmit data representing the rotational speed of mixing drum 12 to computer processor unit 20 or to another processor which is not located on the concrete delivery vehicle.

[038] Computer processor unit 20 is coupled and/or wirelessly connected to an accessible memory unit or units that contain data to correlate amounts of admixture by addition and their effects on drawdown, whereby actual drawdown may be adjusted to or towards the target sag. The aforementioned Verifi patents contain instrumental teachings in this regard, although none of them are directed towards or foresee the benefits to be obtained through the use of PCEs within a specific range of cumulative adsorbity coefficient as taught by the present invention.

[039] As illustrated by Figure 2 in perspective taken along the rotational geometric axis of the concrete mixing drum 12, the concrete mixture 15 is mixed through the rotating action of the rotating drum 12 and the surrounding mixer blades 13A and 13B of the rotational geometric axis (30), the fluidizing chemical addition mixture (designated as in 25) comprises one or more honeycomb type polycarboxylate ether ("PCE") polymers dispersing cement having a cumulative adsorbity coefficient of 40% at 75%, based on the cement constituting the concrete mix 15 in mixing drum 12. The term "adsorbability" refers to the ability of PCE to adhere to hydratable cement particles within the cement particle water suspension, and the concept of cumulative adsorbity coefficient will be explained in more detail hereafter. The actual fundamental working mechanism by which PCEs adhere or attach to cement particles is not fully understood. Such a mechanism is believed to be based on the interaction between the anionic nature of the PCE polymer and the cationic nature of the calcium ion on the surfaces of suspended cement particles in combination with the other entropic terms of the suspension system containing PCE molecules. . Honeycomb-type PCEs are distinguished by the adsorption backbone unit and a hydrophilic polyethylene oxide side chain (or "teeth"), such as when PCEs are adsorbed at the liquid-solid interface in a suspension of (as summarized above), PCEs induce an interparticle repulsive force that prevents the formation of agglomerates and, therefore, enables the flow properties, while reducing the water-to-cement ratio in the cementitious composition. See, for example, Lucia Ferrari et al., "Interaction of Cement Model Systems with Superplasticizers Investigated by Atomic Force Microscopy, Zeta Potential, and Adsoption Measurement," Journal of Colloid and Interface Science 347 (2010) 15 to 24 (available online at March 7, 2010).

[040] The term "cement" as used to describe the present invention includes hydratable cement such as Portland cement which is produced by spraying bricks consisting of hydraulic calcium silicates, aluminates and aluminoferrites and one or more forms of sulfate. of calcium (eg gypsum) as an interground additive. Typically, Portland cement is combined with one or more supplemental cementitious materials such as fly ash, granulated blast furnace slag, limestone, natural pozzolans or mixtures thereof and supplied as a blend. Thus, the term "cement" can also include supplemental cementitious materials that were interground with Portland cement during manufacture.

[041] The term "cementitious" may be used herein to refer to materials that comprise Portland cement or that otherwise function as a binder to hold fine aggregates together (e.g. sand), coarse aggregates ( e.g. crushed gravel) or mixtures thereof, in concrete and mortar. The term "hydratable", as used herein, is intended to refer to cement or cementitious materials that are hardened through chemical interaction with water. Portland cement brick is a partially melted mass composed primarily of hydratable calcium silicates. Calcium silicates are essentially a mixture of tricalcium silicate (3CaO-SiO2 or "C3S" in cement chemical notation) and dicalcium silicate (2CaO-SiO2, "C2S") in which the former is the dominant form, with a smaller amount of tricalcium aliminate (3CaO-Al2O3, "C3A") and tetracalcium aluminoferrite (4CaO-Al2θ3-Fe2θ3, "C4AF"). See, for example, Dodson, Vance H., Concrete Admixtures (Van Nostrand Reinhold, New York, NY, 1990), page 1.

[042] The term "concrete" will be used herein generally to refer to hydratable cementitious mixtures comprising cement, sand and, in general, a coarse aggregate such as crushed stone or gravel and, optionally, a chemical addition mixture. , such as one or more chemical addition mixtures (e.g. one or more PCEs).

[043] The phrase "accumulative adsorbity coefficient" (referred to as Ac), as used herein, means and refers to the adsorbability of one or more honeycomb type PCEs on the hydratable cement that is used to produce the wet concrete or other cement mixture (eg mortar) that is delivered by truck to the dump/construction site. Accordingly, the present inventors believe that, using the teachings of the present invention, it is possible to combine PCE polymer or polymers which may have an extremely high Ac value (above 75%) with the PCE polymer or polymers which may having an extremely low Ac value (below 40%) to achieve a cumulative adsorbity coefficient (Ac) within the present invention (i.e. 40% to 75%).

[044] As mentioned earlier, Figure 3 graphically illustrates the adsorbability behavior of a sample PCE polymer cement dispersant as a function of mixing time. The horizontal axis indicates the mixing time started when the sample mortar cement, water and PCE dispersant(s) are completely mixed together and the vertical axis indicates the adsorbability behavior in percentage of the PCE in cement. The range of the cumulative adsorbity coefficient (Ac) from 40% to 75% is designated by the double arrow in "(a)", which coincides with the 120 second mark (along the horizontal time axis).

[045] The behavior over time of a PC-based polymer cement dispersant that has features of the present invention is plotted over time using solid connected lines, which define a space designated by "(2) ", which appears in Figure 3 between 300 seconds and 1000 seconds after mixing. The present inventors believe that it is useful to think about the behavior of the cement sample mixture containing sample PCE in 300 seconds, as it corresponds to the actual mixing of a corresponding concrete after about 20 revolutions of a concrete mixing drum in a mixing truck; and it is useful to think about the behavior of the cement sample mixture containing PCE in 1000 seconds, as it corresponds to the actual mixing of a corresponding concrete after about 70 revolutions of a concrete mixing drum in a mixing truck, which it is often considered the ideal time or a time frame within which an actual delivered concrete mix load must be unloaded (dump) from the truck at the construction site.

[046] On the other hand, for a PCE that has an Ac value between 40% to 75% as contemplated by the present inventors, Figure 3 also illustrates the adsorbability behavior of PCE polymer(s) that are considered to be very fast in 120 seconds, so that PCE is not available to affect the lowering of the concrete subsequently, during the 300 to 1000 seconds (lab sample) mixing period which was chosen by the present inventors as an approximation of 20 to 70 drum revolutions concrete mixing in a real delivery situation; and this is designated as "(1)" in Figure 3. Also illustrated in Figure 3 is the PCE polymer adsorbity rate which is considered very slow at 120 seconds after continuous mixing of the PCE/cement/water sample mixture , so that it does not affect the lowering of concrete at a later stage (e.g. during continuous mixing of the time period from 300 seconds to 1000 seconds of the sample approaching 20 to 70 revolutions of the corresponding concrete which is mixed in a mixing drum in an actual delivery transit situation); and this is designated in "(1)" in Figure 3. On the other hand, the present inventors set the limits of their ideal cumulative adsorption coefficient (Ac) of the PCE polymer(s) at 40% to 70% which corresponds to the adsorbity coefficient of the dispersing polymer of PCE(s), at 25 degrees Celsius and 120 seconds after continuous mixing, as represented by the letter "(a)" in Figure 3.

[047] The value of Ac can be measured in the laboratory using a depletion method. First, a sample (16 gm of cement in 6.4 gm of mixed water solution per addition) is loaded into a glass tube in the amount of 0.03 to 0.2 percent based on dry weight cement. . The tube is shaken extensively for two minutes (using the mixing device or test tube shaker) and 2 grams of supernatant (capillary water) is removed by filtration using a 0.45 micrometer filter and precisely weighed on a scale. Then, 2 grams of hydrochloric acid (0.8%) is added to the supernatant. Then, deionized water is added to obtain a total 40 grams of a diluted liquid capillary water sample.

[048] The cumulative adsorbity coefficient (Ac) is calculated using the formula Ac = [(A - B)/A] x 100

[049] where A represents the total amount of honeycomb-type polycarboxylate ether (PCE) polymer or polymers added to the cement slurry which is then filtered, B represents the amount of PCE that remains in the obtained capillary water through filtration and in which the measurement of adsorbity and filtration is performed at room temperature (25 degrees Celsius) using analytical equipment capable of measuring the concentration of PCE in capillary water. Such analytical equipment may include equipment that measures Total Organic Content (TOC), a gel permeation chromatography (GPC) equipment and a reflective index detector. The water to cement ratio of the sample is 0.4 and the amount of polymer used will be between 0.03 and 0.5% based on dry weight cement as determined by the standard mortar test; namely, the amount of polymer that would be required to provide a mortar with the same fluidity equivalent to adding 14% additional water to the mortar mix (ie, to achieve 14% water cut).

[050] Figure 4 is another graphical illustration of the response time concept, this time as measured by measuring the energy required to turn a Hobart mixer, to which a commercially available power consumption meter has been attached. The data plotted in Figure 4 were taken on subsequent days (January 19 and 20, 2012) to confirm the reproducibility of the data results.

[051] Figure 5 graphically illustrates the change in energy required by the Hobart mixer motor through the addition of the PCE dispersant to the cement mixture contained in the Hobart mixer. It can be seen that the energy required to mix the sample is stabilized after 550 seconds of the mixing time after the PCE has been introduced into the sample containing cement. The power required to mix the concrete decreased from about 102 to 103 Watts to below 90 Watts after about 100 seconds. Thus, about 14 to 15 watts of power reduction was obtained by using 0.11% by weight of PCE addition in the sample cement mortar (although it should be noted that the power consumption and power reduction Actuals may vary significantly depending on the type of mixer used). After normalizing the power curve, setting the initial mixer power to 1 and the final mixer power to zero (0), as shown in Figure 4, a 90% power reduction point was calculated and the time the point where the power curve meets the 0.1 level, which corresponds to the 90% reduction point, is defined as the "response time". The drop in mixer power shown by the downward curve shown after 550 seconds in Figure 5 suggests that the response time was between 35 and 50 seconds.

[052] Several polycarboxylate ether (PCE) polymer molecules were synthesized and their polymer structures analyzed in order to gain some understanding of PCE structures and their correspondence, if any, to response time. In Table 1 shown below, the present inventors characterize various polymers, including a characterization through the use of polymer absorption via the Total Organic Carbon (TOC) method, and examine the dosage required to achieve a 14 Watt reduction in energy required to mix. the concrete. Table 1 summarizes the response time results. Results include response times ranging from 15 to 100 seconds in terms of reduced mixing time. The present inventors analyzed the data and found that several factors, including the dosage required to achieve a target fluidity, PEG (polyethylene glycol) side chain length, peak molecular weight as determined by Gel Permeation Chromatography (GPC) , the PCE polymer adsorption isotherm, and the extent of crosslinking all strongly influence the polymer response time.

[053] Figure 6 graphically illustrates the relationship between the response time and the adsorbity coefficient of various PCE polymers in terms of percentage adsorbed at the required dosage (to obtain 14% water cut in a cementitious mixture). The present inventors have found that fast responding PCE samples that have less than 20 seconds response time do not exist for PCEs that have extremely high Ac values. Accordingly, the present inventors believe that the present invention, with its emphasis on Ac values in the range of 40% to 75%, is a surprising and critical element in achieving rapid response time.

[054] Although the details of the mechanism are unknown and, without being bound by theory, the inventors assume that the advection of the paste portion of the cement within a concrete mix could be the main driving force to disperse and distribute the polymer from PCE in the mix and achieve faster effects on concrete flowability than could be achieved in real applications where slump monitoring systems are used in concrete delivery vehicles, whereby the concrete load is ideally delivered through, or before the mixing drum has completed a certain number of revolutions (eg 70 to 120). While a lower adsorbity coefficient favors a faster turnaround time, lower absorption also results in a higher dosage (needed to achieve the standard 14% water cut-off in the concrete mix), which is not only costly, but it can also result in a delayed drawdown gain over a longer period of time due to your overdose. Therefore, the present inventors have inventively selected 40% to 75% as the optimal cumulative adsorbity (Ac) coefficient to achieve balanced fast response time performance.

[055] The present inventors have further analyzed the data and believe that certain features of PCE polymers are desirable to achieve the aforementioned cumulative adsorbity (Ac) coefficient. For example, the length of the PCE side chains is important. In general, a shorter side chain length (eg, shorter than 2000 atomic mass units (AMU)) appears to be favorable although there are exceptions. In addition, the molecular weight of the PCE polymer, as determined by GPC, also has an effect on response time. In general, a lower number average molecular weight is believed to be favorable for achieving a faster response time. A peak molecular weight below 40,000 AMU also seems favorable for achieving a faster response time. quick reply.

[056] A higher dosage of PCE in the concrete mix also contributes to achieving faster response times. However, a higher dosage is not desired due to the increased mixing costs per addition. It would be desirable for the addition mixture to have a high dosage efficiency, on the other hand, so that the desired flowability could be obtained with relatively lower adsorption coefficients.

[057] In additional exemplary systems and methods of the invention, at least two PCE polymers are blended by addition to the concrete mix. In yet other exemplary systems and methods, the present inventors believe that at least one of the PCE polymers may have an individual adsorbance coefficient that is greater than 75%, however, when combined with another PCE polymer that has an adsorbance coefficient lower individual, it is possible that the cumulative adsorbity coefficient (Ac) can be adjusted so that it falls within its optimal range of 40% to 75%. Similarly, in other exemplary embodiments, the present inventors believe that it is possible for at least one of said PCE polymers to have an individual adsorbity coefficient that is less than 40%, however, when combined with one or more polymers of PCE that has a higher individual adsorbity coefficient, it is possible that the cumulative adsorbity coefficient (Ac) of PCE polymers can be adjusted so that it falls within their ideal range of 40% to 75%. In further exemplary systems and methods of the invention, the present inventors envision that at least three PCE polymers may be admixed by addition to the concrete mix and that it is possible for at least two of the three PCE polymers each to have individual adsorbance coefficients. greater than 75%, however, by blending with one or more of the other PCE polymers that have much lower individual adsorbance coefficients, the cumulative adsorbity coefficient (Ac) can be adjusted to fall within its optimal range of 40 % to 75%. In this regard, the present inventors also envision that at least three PCE polymers can be mixed by addition to the concrete mix, wherein at least two out of the three PCE polymers have an individual adsorbance coefficient that is less than 40%, however, when combined with one or more PCE polymers that have a higher individual adsorbity coefficient, it is possible that the cumulative adsorbity coefficient (Ac) of the PCE polymers can be adjusted to fall within their optimal range of 40% to 75%.

[058] For this reason, additional exemplary embodiments of the present invention are directed to the use of two or more PCE polymers, wherein at least one of the PCE components has an individual adsorbance coefficient that is above or below the range of 40% to 75%. The absorptive capacity of PCE polymers is typically controlled by altering the ratio between (a) the anionic groups that adhere to the cement particles and these are typically carboxylic, phosphoric, or phosphonic acids and (b) the side chains that contain polyoxyalkylene groups (eg ethylene oxide groups) which are sometimes called "PEG" groups as they are typically derived from polyethylene glycol. The greater the amount of acid, the greater the adsorption capacity. A longer PEG side chain length generally allows for a lower amount of acid without entirely impairing adsorption. The most direct approach to decreasing adsorbity, however, is to decrease the ratio of acid to ester groups within the side chain. However, if the acid to ester ratio is too low, the PCE becomes overly sensitive to the type of cement, the cementitious and filler powders used, and the ionic environment and alkalinity of the cementitious mixture. The present inventors also believe that the degree or extent of cross-linking in the dispersing polymer structure is another approach to controlling the polymer's adsorbity coefficient. The present inventors have found that introducing cross-linking to a relatively low degree can decrease the adsorbity of the molecule without decreasing the acid content and thus distributing the acid to ester ratio in the polyoxyalkylene (cement-dispersing) side chains, to position the adsorbity coefficient within the optimal range of 40% to 75% envisioned by the present inventors, who believe that this may further help control adsorption without unnecessarily increasing the sensitivity of the PCE polymer to the cement type. Crosslinking within the polymer can be either permanent or transient.

[059] In short, the present inventors believe that having a high efficiency in combination with controlled adsorption is an important attribute for PCE polymers to achieve fast response time in a practical and effective manner. The ideal polymer has the lowest possible dosage needed for target feasibility with the adsorption coefficient in the range of 40% to 75%, so that there is excess polymer available in the capillary water even when the PCE polymer reaches a high fluidity within the cement mixture.

[060] Exemplary honeycomb-type polycarboxylate ether (PCE) polymers suitable for use in the present invention comprise carbon-containing backbone and pendant groups represented by structures (I) and (II) as represented by the structures below:

[061] wherein each R1 independently represents a hydrogen atom or a methyl group (-CH3 group); M represents a hydrogen atom, an alkali metal or alkaline earth metal cation, ammonium or organic amine groups or a mixture thereof; Alk represents a C2 -C10 alkylene group; p represents an integer from 0 to 1; x represents an integer from 1 to 10; y represents a number from 0 to 300; z represents a number from 1 to 300: R2 represents a hydrogen atom or a hydrocarbon group having from 1-10 carbon atoms; and "a" and "b" are numerical values representing a molar percentage of the polymer backbone, wherein "a" is from 30 to 90 and "b" is from 10 to 70; and

[062] Alternatively and/or optionally, structures (III), (IV) and (V) shown below

[063] wherein Ri represents a group selected from -C(O)O-, -C(O)NH- , -CH2O-, -O-, -(CH2)K- 0(R)(CH2)k- , or a mixture thereof;

[064] wherein R2 represents a group selected from -C(O)O-, -SO3; - PO3", -OPO3-, -Si(OR)3, OSi(OR)3, or a mixture thereof; and

[065] wherein R3 represents -C(O)O-, -CH2 -C(O)-O-, or a mixture thereof;

[066] R represents hydrogen or a C1-C3 alkyl residue;

[067] k represents an integer; and

[068] where "c", "d" and "e" are numerical values representing a molar percentage of the polymer structure, where "c" is from "10 to 70", "d" is from 0 to 90 and "e" is from 0 to 90.

[069] In addition to the monomers used in the above base honeycomb-type polycarboxylate ether (PCE) polymers, any types of known cross-linking agents can be employed to control the degree of cross-linking of PCE polymers, as shown in the examples below.

[070] While the invention is described herein using a limited amount of embodiments, these specific embodiments are not intended to limit the scope of the invention as otherwise described and claimed herein. There is the modification and variations of the described modalities. More specifically, the following examples are provided as a specific illustration of embodiments of the claimed invention. It should be understood that the invention is not limited to the specific details set forth in the examples.

[071] All parts and percentages in the examples, as well as the remainder of the specification, are by weight percentage, unless otherwise specified.

Example 1 (Polymers synthesized in the laboratory) i. Response Time Measurement

[072] The response time measurement is performed through a cement mortar mixture test which is described as follows. The mortar mix has a water to cement (w/c) ratio of 0.40 of Mortar and the cement, sand and water (C/S/W) ratio is 1,264/2,700/506. The mortar mixes were prepared in 2 liter batches in a mixer with power (correlated to workability) measured over time. Predetermined amounts of cement dispersion PCE polymers were introduced to the mortar mixture contained in the mixer after the mixer's power consumption was stabilized (indicating that the cement mortar was uniformly mixed). The introduction of dispersant quickly reduced engine power. The power reduction was recorded using a lap top computer. An anti-foaming agent was used for all addition mixes containing PCE. Power normalization through time curves was performed by calculating the time required to reduce power consumption by 90%.

B. Polymer Synthesis (designated as Series 19213 and 19269)

[073] Monomeric starting materials were obtained from Aldrich (Poznan, Poland). PCE polymers were prepared as copolymers of monomethoxypolyethylene glycol methacrylate and acrylic acid with a varying ratio of monomers and a varying amount of the crosslinking agent, diethylene glycol diacrylate. Different monomers were used to change the final polymer structure. For this reason, conventional chain transfer agents have been used to form honeycomb-type PCE polymers designated as series 19213 and 19269 in Table 1 above) with the use of the following: (1) for the formation of the pendant side chains (or "teeth"): methoxypolyethylene glycol methacrylate ("MPEGMA") (which has a molecular weight of 2080 and 1000); (2) anionic monomer: acrylic acid ("AA"); and (3) as a crosslinking agent: diethylene glycol acrylic diacid ("DEGDA").

[074] The polymers were prepared through a semi-batch process using a conventional radical polymerization in water. All polymers were prepared following the same procedure: In a 500 ml bottle containing between 30 and 80 grams of water. One syringe was loaded with 20 grams of MPEGMA, the other monomers, mercaptopropionic acid as a chain transfer agent (CTA) and 10 grams of water and the other syringe containing 1 gram of ammonium persulfate as an initiator and 10 grams of deionized water. . The two solutions were simultaneously added via syringe pump over 1 hour at 70°C under continuous stirring (80 rpm). The final product was tested without further purification.

[075] The total water used was calculated to obtain a final total solids content of 20% by weight.

[076] A summary of the reagents used in polymer formulation is provided in Table 2 below.

C. Polymer Synthesis, Series 19181 (methallylsulfonate method)

[077] The prescribed amounts of MPEGMA monomers, sodium methacrylate (Na-MA) and sodium methallylsulfonate (SMAS) were loaded into a four-neck flask fitted with a thermocoupled mechanical stirrer using a reflux condenser and nitrogen input. SMAS was used as a molecular weight control agent. The slow flow of nitrogen gas was started and the monomer solution was heated to 60 degrees Celsius. 20% by weight ammonium persulfate was added via funnel over a period of one minute. The reaction temperature was maintained at 60 degrees Celsius (plus or minus 2 degrees) for 3.5 hours. The reaction mixture was allowed to cool to room temperature. The solution was used in the mortar test in such a way.

[078] The molar ratios of the monomers used in the present example are summarized in Table 3 below.

D. Polymer characterization

[079] Absorption isotherm. Chemical fluidizing addition mix adsorption to cement was measured according to available literature using the Total Organic Carbon ("TOC") method (See, for example, Ferrari et al., Journal of Colloid and Interface Science, 347(2010) 15 to 24). For each dose of dispersant investigated, 16 g of cement was first introduced into a centrifuge tube, followed by the addition of 6.4 g of a solution of the mixture by addition with deionized water (18.2 MQ.cm) to obtain a ratio of water to cement of 0.4. Addition mix concentrations were chosen to investigate doses of 0.03, 0.06, 0.08, 0.1, 0.12, 0.15 and 0.2 percent dry weight based on cement weight. (e.g. 0.03% required a 0.75 g/l addition mix solution). The tube was then shaken for two minutes in a VWR Vortex 444-1372(EU) mixer. Approximately two (2) grams of the supernatant were separated using a 0.45-μm filter and accurately weighed into a 50 ml tube. Then, two grams of HCl (0.8%) were added and the tube was filled with deionized water to reach a final weight of 40 grams. At the same time, a sample was prepared with the addition mixing solution only, using the same procedure as described above, i.e. 2 grams of HCl (0.8%) constituting the total weight of 40 grams. The amount of pure solution was exactly the same as the amount of supernatant tested previously.

[080] An additional blank solution was prepared, using only deionized water and cement instead of the addition mix solution, still using the same procedure, i.e. two grams of HCl (0.8%) and filling with deionized water to make up 40 grams.

[081] The TOC content was analyzed on a measuring device, Elementary™ High TOC II, and the amount of polymer adsorbed by the cement was as determined for each dose using the following formula:

Percent adsorbed = (TOC - TOCref) \ TOCref

[082] where TOC represents the Total Organic Carbon measured for the supernatant minus the blank solution (TOC = TOC supernatant minus TOC blank solution); and TOCref is the Total Organic Carbon measured for the pure solution of the admixture mixture.

E. Gel Permeation Chromatography (GPC)

[083] GPC chromatograms were recorded with the following program: (1) columns: Waters Ultrahydrogel Guard™, Waters Ultrahydrogel™ 1000, Waters Ultrahydrogel™ 250 and Waters Ultrahydrogel™ 120 Column; (2) Detector: R1; (3) mobile phase: 1% potassium nitrate; (4) Flow rate: 0.6 ml/min.; (5) running time: 100 min.; and with the use of (6) polyethylene glycol standards.

Example 2 (Commercially available polymers)

[084] Similar to the above laboratory polymers, several commercial polymers were also tested for response time and adsorbity coefficient. Table 4 shows the results.

[085] Figure 7 shows the relationship between the response time and the adsorbity coefficient of some commercially available PCE cement dispersants. Similar to laboratory synthesized polymers, a general trend towards lower adsorbity and faster response time can be observed. The fastest polymer is designated as "(5)" in Figure 7. However, as can be seen from Table 4, the dosage required to achieve target feasibility is significantly higher compared to other PCE samples. Therefore, the present inventors do not believe that such a sample polymer is suitable when used alone to achieve fast response time in accordance with the purposes of the present invention.

[086] On the other hand, PCE sample "1" appeared to have adequate dosing efficacy, however, on the other hand, the response time for this sample was observed to be very slow compared to the others, as shown in Figure 7. Therefore, the present inventors do not believe that such a sample polymer is suitable when used alone to achieve adequate rapid response time in accordance with the purposes of the present invention.

[087] The sample PCE designated "2" appeared to demonstrate both balanced dosing efficacy and response time falling within the scope of the present invention. The polymer dosing behavior of the various PCE polymers from sample 1 to 5, as a function of the adsorption rate at 120 seconds (after a thorough mixing of PCE, cement and water), is graphically illustrated in Figure 8.

[088] The aforementioned illustrations and examples are provided for illustrative purposes only and are not intended to limit the scope of the invention.

Claims (2)

1. Method for achieving a fast turnaround time of a polycarboxylate ether polymer in a concrete mix, CHARACTERIZING by comprising: providing a rotating mixing drum to contain a hydratable concrete mix; provide a system for continuously monitoring the slump of the hydratable concrete mix contained in the rotating mixing drum and for dispensing controlled amounts of fluidizing chemical addition mix into the concrete mix within the drum on the basis of continuous monitoring; and providing a fluidizing chemical addition mixture to be dispensed through the system, wherein the addition mixture comprises at least one honeycomb-type polycarboxylate ether polymer to modify the slump of the concrete mixture, the polymer having an accumulative adsorbability coefficient. (Ac) from 40% to 75% as determined by a depletion method whereby a sample of the polymer is loaded into an aqueous cement slurry containing the cement used to produce the hydratable and mixed concrete mix, together, and separated after 120 seconds continuous mixing of the aqueous cement slurry to obtain supernatant capillary water, according to the formula Ac= [(A - B)/A] x 100 where A represents the total amount of polymer added to the aqueous cement slurry which was then separated to obtain the supernatant capillary water, B represents the amount of polymer remaining in the supernatant capillary water obtained by separating the aqueous cement slurry, and wherein the adsorbity is measured at 25° Celsius in the supernatant capillary water separated from the aqueous cement slurry after continuous 120 second mixing of the cement-containing aqueous cement slurry, water and the polymer, wherein the water to cement ratio of the slurry is 0.4 and the amount of the polymer metered into the aqueous cementitious slurry is between 0.03% to 0.5% by dry weight based on the The dosage of cement and polymer used is calculated through the mortar test, whereby the dosage for the polymer is that which provides the same fluidity as the addition of 14% additional water to the aqueous cementitious slurry, in which the system is programmed to continuously monitor and adjust the slump by introducing the fluidizing chemical addition mixture into the concrete load, and to iteratively repeat the monitoring and adjustment steps during transit and/or upon arrival n the pour/delivery site, wherein the method comprises dosing the mixture by fluidizing chemical addition into the concrete mixing drum containing the hydratable concrete mix during transit and/or upon arrival at the pour/delivery site, and wherein the peak molecular weight of the polycarboxylate ether polymer determined by GPC is below 40,000 atomic mass units AMU. 2. Method, according to claim 1, CHARACTERIZED by the fact that the system for continuous monitoring of the lowering of the hydratable concrete mixture contained in the rotating mixing drum and for dispensing controlled amounts of mixture by fluidizing chemical addition into the mixture of concrete inside the drum based on continuous monitoring comprises a sensor selected from the group consisting of hydraulic pressure sensor, electromechanical sensor or a combination thereof.

Images